I was looking for a way to track my caffeine intake, as well as the caffeine decay in my body (by approximation). That got me the idea to build a custom HACS (together with my friend Claude code), that allows you for your whole household 
Features:
- Current mg in your body (live, decaying in real time)
- Total intake today
- A “Sleep Safe At” timestamp, when you’ll drop below your threshold
- Estimated peak level if absorption mode is on
This is how it could look on your dashboard:
(left to right: current caffeine, total taken caffeine today, number of consumptions, time until ready for bed).
logging a consumption is done here with a button, but you could do it from your apple watch, NFC tag etc
sharing it here, in case anyone is interested: GitHub - evanraalte/hacs-caffeinetracker · GitHub
In case you like it / miss features / have other ideas, please let me know!